An automotive vehicle is provided with an air conditioning system for controlling the temperature of a vehicle room air. As shown in FIG. 1, a conventional air conditioning system includes an air conditioning case 10 in which a blower 20 is installed. In general, the air conditioning case 10 is arranged inside of an instrument panel in front of a passenger seat.
The blower 20 includes a blower fan 22 and a blower motor 24 for driving the blower fan 22. The blower 20 serves to inhale an external air or an internal air and then to feed the inhaled air to an internal passageway 12 of the air conditioning case 10.
The air conditioning system further includes an evaporator 30 arranged inside the internal passageway 12 of the air conditioning case 10. The evaporator 30 includes a plurality of coolant tubes (not shown) through which coolant can flow. The evaporator 30 serves to cool the air passing through the internal passageway 12 and also to introduce the cooled air into a vehicle room, thereby keeping the vehicle room at a pleasant temperature.
The air conditioning system further includes an ionizer 40 for emitting positive ions and negative ions toward the air flowing through the internal passageway 12. As illustrated in FIGS. 1 and 2, the ionizer 40 is installed on the upstream side of the evaporator 30 and includes a main body 42 attached to a side wall of the air conditioning case 10, and first and second discharge electrodes (44, 46) extending from the main body 42 into the internal passageway 12 in a spaced-apart relationship with each other.
The main body 42 is provided with joint pieces 42a at its peripheral edge. The joint pieces 42a are fixedly secured to the air conditioning case 10 by driving screws 42b into a side surface of the air conditioning case 10 through the joint pieces 42a. 
The first and second discharge electrodes (44, 46) are arranged one above the other in a spaced-apart relationship with each other and extend into the internal passageway 12 through electrode insertion holes 14 formed in the air conditioning case 10. The first and second discharge electrodes (44, 46) are designed to generate negative ions and positive ions by irradiating high voltage pulses into the air flowing through the internal passageway 12.
The negative ions and positive ions generated in the ionizer 40 are introduced into the evaporator 30 to sterilize bacteria and mold living in the evaporator 30 and also to deodorize the air supplied into the vehicle room, thereby enhancing the degree of cleanliness of the air introduced into the vehicle room and creating a comfortable vehicle room environment.
However, the conventional air conditioning system referred to above poses a problem in that it is very difficult to separate the ionizer 40 when the ionizer 40 is removed from the air conditioning case 10 to repair or replace the same.
In other words, since the air conditioning case 10 is installed inside the instrument panel in front of the passenger seat, the spare space left around the air conditioning case 10 is very narrow and small. In particular, as can be seen in FIG. 2, a dash board 16 is arranged near the air conditioning case 10 at a narrow interval, which leaves a small space between the dash board 16 and the ionizer 40. This makes it difficult to insert a tool and loosen the screws 42b. Even after the screws 42b are loosened and removed, it is very inconvenient and difficult to demount the ionizer 40 from the air conditioning case 10.
Consequently, the conventional air conditioning system is problematic in that it is very difficult to detach the ionizer 40 from the air conditioning case 10 and to attach the same to the air conditioning case 10.
In addition, the first and second discharge electrodes (44, 46) of the ionizer 40 are arranged one above the other in the conventional air conditioning system. This leads to a drawback in that the moisture condensed in and around the upper first discharge electrode 44 flows toward the lower second discharge electrode 46. Such a drawback poses a problem in that the first and second discharge electrodes (44, 46) may be electrically connected to each other. The electrical connection may cause a spark between the first and second discharge electrodes (44, 46), consequently generating a discharge noise.